XDMA_DESC_CONTROL
XDMA_DESC_CONTROL(1, XDMA_DESC_STOPPED | XDMA_DESC_COMPLETED)
XDMA_DESC_CONTROL(1, XDMA_DESC_COMPLETED)
desc_control = XDMA_DESC_CONTROL(XDMA_DESC_ADJACENT, 0);
desc_control = XDMA_DESC_CONTROL(last_blk_desc + 1, 0);
control = XDMA_DESC_CONTROL(1, 0);